The present invention relates generally to a wave forming apparatus and is partially concerned with water rides of the type provided in water-based amusement parks, particularly a wave forming apparatus and method for forming surfable waves, or a water toy.
Naturally occurring waves occur in the ocean and also in rivers. These waves are of various types, such as moving waves which may be of various shapes, including tubular and other breaking waves. A relatively rare type of wave in nature is the standing wave, which has a steep, unbroken and stable wave face. This type of wave can have enough power and velocity to support surfing on the wave face without causing the wave to decay rapidly. This wave, if forced to decay, for example by overly obstructing the flow, reforms naturally when the obstructions are removed. Natural standing waves have been shown to occur where water flows across natural river bed formations, known as anti-dunes. Upon flow over anti-dunes, the water flow rises into a natural standing wave. Natural standing waves occur in the Waimea Bay river mouth of the Waimea River on the Hawaiian island of Oahu, on the Snake River in Wyoming, and several other places.
Surfers are constantly searching for good surfing waves, such as tubular breaking waves and standing waves. There are only a few locations in the world where such waves are formed naturally on a consistent basis. Thus, there have been many attempts in the past to create artificial waves of various types for surfing in controlled environments such as water parks. In some cases, a sheet flow of water is directed over an inclined surface of the desired wave shape. Therefore, rather than creating a stand-alone wave in the water, the inclined surface defines the wave shape and the rider surfs on a thin sheet of water flowing over the surface. This type of apparatus is described, for example, in U.S. Pat. Nos. 5,564,859 and 6,132,317 of Lochtefeld. In some cases, the inclined surface is shaped to cause a tubular form wave. Sheet flow wave simulating devices have some disadvantages. For example, since these systems create a fast moving, thin sheet of water, they produce a different surfing experience to a real standing wave.
In other prior art wave forming devices, a wave is actually simulated in the water itself, rather than being defined by a surface over which a thin sheet of water flows. U.S. Pat. No. 6,019,547 of Hill describes a wave forming apparatus which attempts to simulate natural anti-dune formations in order to create waves. A water-shaping airfoil is disposed within a flume containing a flow of water, and a wave-forming ramp is positioned downstream of the airfoil structure. In other prior art arrangements, such as U.S. Pat. No. 3,913,332 of Forsman, a wave generator is driven around a circular body of water in order to create waves. This arrangement is also complex and will produce traveling waves, not standing waves.
It is an object of the present invention to provide a new and improved wave forming apparatus and method.
According to one aspect of the present invention, a wave forming apparatus is provided, which comprises a channel for containing a flow of water, the channel having an inlet end connected to a water supply, a base, and spaced side walls, a weir in the base at the inlet end of the channel, and at least one bed form in the channel downstream of the weir, the bed form having a leading end and a trailing end, an upwardly inclined upstream face extending downstream of the leading end, an upper portion, and a downwardly inclined downstream face extending from the upper portion to the trailing end, the weir and bed form each extending outwardly to the side walls to define a primary water flow path from the inlet over the weir and bed form, and a secondary flow passageway provided in the channel, the secondary flow passageway having a first end communicating with the primary water flow at a location adjacent the trailing end of the bed form, and a second end communicating with the primary water flow at a location upstream of the first end.
In an exemplary embodiment of the invention, the first end of the secondary flow passageway comprises a first vent extending across the full width of the bed form. The second end may comprise a second vent extending across the full width of the bed form, or may comprise spaced second vents adjacent opposite sides of the bed form, each vent extending across the upper portion of the bed form. The first and second vents may be connected together via ducting or passageways through the bed form. Alternatively, the bed form may comprise a hollow shell so that the vents communicate via the chamber within the hollow shell.
This arrangement will tend to create a standing wave at the leading end of the bed form and any subsequent bed form. The provision of a secondary flow channel within the bed form communicating with a vent at the trailing edge of the bed form will enhance production of a stable standing wave at the next bed form in the channel, where two or more successive bed forms are provided. A secondary flow passageway may also be provided in the weir. In the exemplary embodiment, the side walls of the channel do not extend vertically upwardly from the top of the bed forms, but instead have outwardly angled, shallow inclined portions which taper slowly upwardly from the opposite sides of the weir and bed forms. Alternatively, the side portions on opposite sides of the channel extend outwardly either horizontally or at a slightly downwardly inclined angle on opposite sides of the channel containing the bed forms. In practice, the outer side portions or side walls may extend outwardly from the channel at an angle relative to the horizontal of +10xc2x0 to xe2x88x925xc2x0. This has been found to enhance the standing wave formation capabilities of the apparatus, and also provides a shallow lead-in portion for individuals prior to riding a standing wave, and for exiting the ride.
Water flows along the secondary flow passageway in either direction, depending on the conditions. It has been found that the provision of the secondary flow path enhances the formation of a stable standing wave at the upstream face of the bed form, and at any other bed forms downstream of the first bed form. Thus, additional secondary flow passageways will be provided, one for each wave-forming bed form. Adjustable valves or the like may be provided in the secondary flow passageways in order to vary the secondary flow rate. Additionally, several separate gates may be provided across the width of the first vent or the flow passageway, and these gates, if closed sequentially, can produce a lateral breaking wave.
In an exemplary embodiment of the invention, the trailing end of the bed form has an abrupt vertical drop off, such that the uppermost region of the trailing end is raised up above the channel bottom by a predetermined tail elevation. This has been found to enhance the standing wave formation properties of the apparatus. In fact, with an abrupt trailing end drop off in the waveform in a predetermined elevation range, the secondary passageways may be eliminated altogether, and standing waves may still be created. The tail elevation factor (TEF), or ratio of the top surface distance at the trailing end of the bed form above the channel bottom to the elevation of the top or peak of the next bed form above the channel bottom, may be in the range from 0.125 to 0.75 while still producing a rideable standing wave. Waves will still be produced at ratios above 0.75.
The tail elevation need not be constant across the entire width of the bed form. For example, TEF may be zero at one side of the channel and 0.8 at the other side. The tail elevation may be permitted to self-adjust based on water pressure. This will produce an oscillating wave.
In an exemplary embodiment of the invention, a series of identical bed forms are provided at spaced intervals along the channel, so that a series of standing waves may be formed. The channel cross section may be deeper in the wave forming area than at the outer sides of the bed forms, and may have gradually outwardly sloping side walls. This tends to return water to the center of the flume or channel, and also prevents too much water from escaping around the sides of the bed forms.
According to another aspect of the present invention, a method of forming waves is provided, which comprises the steps of directing water from a reservoir at one end of a channel having a base and spaced side walls into the channel and over a weir at the inlet end of the channel, directing water in the channel in a primary flow path over at least one bed form in the channel downstream of the weir, the bed form having a leading end and a trailing end, an upwardly inclined upstream face extending downstream of the leading end, an upper portion, and a downwardly inclined downstream face extending from the upper portion to the trailing end, and directing a secondary flow of water along a secondary flow passageway having a first end communicating with the primary water flow at a location adjacent the trailing end of the bed form, and a second end communicating with the primary water flow at a location upstream of the first end, whereby a stable standing wave is formed downstream of the bed form.
This invention provides a wave generating apparatus and method particularly suitable for use in water park rides and the like which is able to produce more consistent and controllable standing waves than was possible in the past. The waves will be of good quality, enabling surfers to ride for a longer period of time without the wave decaying.